US and Iraqi troops on a joint patrol in Baghdad in 2009. The White House has said it doesn't need authorization from Congress to send 300 US military advisers to Iraq. (AHMAD AL-RUBAYE/AFP)

WASHINGTON — Absent from the White House’s formal notification to Congress of a deployment of US military advisers to Iraq is any mention of the 2001 resolution that authorized force against al-Qaida and related groups.

The notification hit Capitol Hill just as both chambers were wrapping up work and heading out for a weeklong July 4 recess, arriving just as some lawmakers are calling for a new use-of-force measure if President Barack Obama opts for US airstrikes in Iraq — and, perhaps, Syria.

Obama’s deployment of 300 US military advisers to Iraq “is being undertaken ... pursuant to my constitutional authority to conduct US foreign relations and as commander in chief and chief executive,” Obama wrote in a Thursday letter to the House speaker and Senate president pro tempore.

The letter came one day after Sen. Tim Kaine, D-Va., took to the Senate floor to declare any US military operations against a violent Sunni group, the Islamic State of Iraq and the Levant (ISIL), would fall outside the scope of the post-9/11 authorization of the use of military force (AUMF).

“Congress passed an [AUMF] immediately after ... the 9/11 attacks to allow action against those who perpetrated the attacks on that day,” Kaine said Wednesday. “ISIL had no connection with the 9/11 attacks. ISIL did not form until 2003.

“It would be a wholly unprecedented stretch to suggest that the 2001 AUMF would justify action against ISIL in Iraq,” he said.

On Thursday, Kaine told CongressWatch that there is “broad support” from senators in “both parties” to revise and update the 2001 resolution to reflect a changed al-Qaida and the conception of new violent extremist groups like ISIL.

The White House told CongressWatch it has determined deploying the military advisers “does not require an authorization to use military force.”

Notably, spokeswoman Caitlin Hayden signaled the White House is open to discussions about a new use-of-force resolution should Obama decide direct military action is necessary to beat back ISIL.

“We have said that the president has committed to continue to consult with Congress,” Hayden said. “We have said that he has not decided to take military action, but should he make such a decision, then we can talk about whether additional approvals or authorities might apply. And we also said that we continue to support the repeal of the Iraq AUMF.”

The latter was a reference to a separate use-of-force resolution Congress approved in late 2002, which Obama has repeatedly said should be voided.

The 2001 AUMF gives the president the authority to “use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on Sept. 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.”

Some national security experts and legal scholars — joined by Democratic and Republican lawmakers — say the post-9/11 measure is outdated and cannot be used in perpetuity.

A Stanford University task force recently wrote that actions like drone strikes in Somalia and military operations against groups that sprang up after 2001 fall outside the legal bounds of the post-9/11 measure.

The AUMF’s use for all US military actions against all so-called terrorist groups “is increasingly difficult as newer threatening groups emerge with dimmer ties, if any, to al-Qaeda. As a result, we are reaching the end point of statutory authority for the president to meet terrorist threats,” that task force wrote.

Mieke Eoyang of think tank Third Way wrote in a May piece that “now it is time to revisit the AUMF.”

“Starting over with a blank slate,” she wrote, “is better than going forward with a blank check.” ■